EP1239166A1 - Linear actuator of cylindrical type - Google Patents

Linear actuator of cylindrical type Download PDF

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Publication number
EP1239166A1
EP1239166A1 EP02004445A EP02004445A EP1239166A1 EP 1239166 A1 EP1239166 A1 EP 1239166A1 EP 02004445 A EP02004445 A EP 02004445A EP 02004445 A EP02004445 A EP 02004445A EP 1239166 A1 EP1239166 A1 EP 1239166A1
Authority
EP
European Patent Office
Prior art keywords
piston
pressure
inner cylinder
cylinder
uni
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02004445A
Other languages
German (de)
English (en)
French (fr)
Inventor
Carlo Brisighelli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
IROSS Srl
Original Assignee
IROSS Srl
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by IROSS Srl filed Critical IROSS Srl
Publication of EP1239166A1 publication Critical patent/EP1239166A1/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/204—Control means for piston speed or actuating force without external control, e.g. control valve inside the piston
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • F15B11/036—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of servomotors having a plurality of working chambers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50545—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using braking valves to maintain a back pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • F15B2211/5154—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve being connected to multiple ports of an output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7055—Linear output members having more than two chambers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/775—Combined control, e.g. control of speed and force for providing a high speed approach stroke with low force followed by a low speed working stroke with high force, e.g. for a hydraulic press

Definitions

  • the invention concerns a hydraulic fluid linear actuator made by means of two coaxial cylinders which is used advantageously in applications in which maximum force is required only during an interval less than the total travel of the actuator, whereas a high speed of approach and return is required.
  • a typical field of application is presses, press-benders, wood-cutting or trunk-cutting machines, hydraulic shears and similar machines.
  • presses and similar machines which have a working principle based on the force generated by a fluid pressure, are equipped with a hydraulic jack as a power actuator.
  • a hydraulic jack as a power actuator.
  • variable delivery pumps generally with pistons or blades, controlled by the fluid pressure by means of a circuit which keeps constant the power absorbed by the pump or the torque required by the pump.
  • This solution entails using costly apparatus and is applied on high category machines.
  • the hydraulic circuit has to be sized according to the maximum delivery supplied by the pump.
  • Another solution is to use circuits of a regenerative type, in which the hydraulic jack is driven in its approach, by connecting both the chamber on the rod side and also the rear chamber behind the pressurized branch of the circuit; in this way the flow emerging from the front chamber is added to the flow generated by the pump and conveyed into the rear chamber.
  • This solution appears quite economical and can be controlled both manually, by acting on a suitable distributor, and also automatically, by means of valves which switch the circuit when a threshold pressure is reached, determined by the contact of the tool with the piece being worked.
  • this solution which is generally used on jacks with a rod area equal to half the area of the cylinder, does not allow to reach considerable factors of increase in the cycle speed compared with the simple circuit (max 1.5).
  • a further solution, adopted in shears for the demolition of concrete, is to use a "pressure intensifier", consisting of a double section cylinder separated from the main cylinder, in which a quantity Q of fluid entering at pressure P determines a theoretic quantity Q/n of fluid emerging at pressure n ⁇ P.
  • a group of valves feeds the jack at the pressure generated by the pump until contact with the piece; once contact has been made, the fluid pressure is sent to the intensifier whose outlet feeds the jack at the higher pressure.
  • This technique requires to use numerous components designed to work at the intensified pressure, hence costly and critical components. This solution is therefore only indicated when the bulk sizes of the conventional components are excessive and it is therefore convenient to operate at high pressures, which are incompatible with normal hydraulic pumps.
  • the main purpose of the invention is to obtain a device or component and the relative circuit, able to move with greater speed during the approach step, that is, during the step where the resistant force is less than a determined threshold, and to move with a lesser speed and at maximum force when the resistant load generated by the working process requires it, and then continue to move at a greater speed when the working process is finished.
  • the linear actuator consists of two hydraulic cylinders, one inside the other and both equipped with a rod in common: the inner actuator, with a smaller section, represents the rapid movement system, while the outer actuator constitutes the component able to generate, under pressure from the pump, the force necessary to carry out the working process.
  • the bottom of the inner cylinder constitutes the piston of the outer cylinder and will be called hereafter in the description "bottom-piston”.
  • a uni-directional valve is housed on said bottom-piston, and allows free passage from the rear chamber of the outer cylinder to the rear chamber of the inner cylinder and not vice versa. Said valve is kept mechanically open by the contact between the bottom-piston and the bottom of the outer cylinder, in which case the fluid will be free to emerge from the inner rear chamber to the outer rear chamber.
  • the front chamber of the inner cylinder communicates directly, by means of several holes, with the front chamber of the outer cylinder.
  • front chamber we mean the chamber on the rod side.
  • a valve is mounted on the pipe that feeds the front chamber and is piloted by the pressure present on the rear chamber to prevent the fluid from emerging freely until the pressure P 2 present in the front chamber exceeds the value given by the formula P 2 ⁇ P t - k ⁇ P 1 where P t represents the setting value of the valve, k the pilot ratio of the valve, P 1 the pressure in the rear chamber of the outer cylinder.
  • the afore-mentioned valve is of uni-directional balancing type.
  • the fluid pressure conveyed into the rear chamber of the outer cylinder flows through the uni-directional valve inside the inner cylinder causing it to advance rapidly.
  • the rod meets a slight resistance to this advance and the counter-pressure in the front chambers is given by the solution of the following formulas of the geometry of the cylinder and the characteristics of the valve:
  • the fluid pressure increases by the resistance to the advance, causes the bottom-piston to be distanced from the rest position and consequently the uni-directional valve located therein to be closed; in these conditions, the fluid pressure which acts on the bottom-piston determines an increase in the inner pressure of the minor actuator, which is totally closed by the uni-directional valve; in these conditions the pressure rises to values determined by the ratio of the respective areas of the cylinders in the same way as a pressure intensifier.
  • the reduction in the pressure caused by the lesser resistance to advance causes the uni-directional valve located on the bottom-piston to open, the smaller cylinder will start again its respective advance at a higher speed while the bottom-piston will retreat due to the counter-pressure of the front chambers until it comes into contact with the bottom of the larger cylinder.
  • the preferential form of the uni-directional valve located on the bottom of the cylinder consists of a valve with a conical seating on whose rod, protruding from the base of the bottom-piston, a precharging spring will be mounted.
  • the uni-directional valve may consist of a ball embedded in the bottom-piston which is opened thanks to a pin solid with the bottom of the outer cylinder.
  • the piston of the outer cylinder may be not integrated with the bottom of the inner cylinder, but located in any position whatever of said cylinder.
  • the piston and relative seal could even be integrated with the head of the inner cylinder.
  • the uni-directional balancing valve located in correspondence with the feed pipe of the front chambers can be replaced by a hydraulic release uni-directional valve.
  • a conical seating is provided for lodging the uni-directional valve 30, a stem 31 of which protrudes from the rear part of the same bottom-piston 16.
  • the valve 30 is normally closed by a spring 32 coaxial with the stem 31.
  • the hydraulic fluid can therefore pass freely from the rear chamber 2 of the outer cylinder 9 to the rear chamber 4 of the inner cylinder 20 through holes 33, but not vice versa, except when the bottom-piston 16 is totally retreated; in this condition the stem 31 of the uni-directional valve 30 hits the bottom wall 13 and causes the forced opening of said valve 30.
  • Fig. 4 represents the operating sequence of the device.
  • Fig. 4a shows the bottom-piston 16 totally retreated.
  • the fluid pressure applied to the outer rear chamber 2 through the pipe 14 passes through the valve 30 and is transmitted to the inner rear chamber 4 of the inner cylinder 20, generating a thrust both on the inner piston 26 and also on the bottom-piston 16; the counter-pressure generated in the front chambers 3 and 5, thanks to the uni-directional balancing valve 7 (not shown in Fig.
  • the rod 10 will be able to continue to advance only if the resistant force is overcome by the force generated by the inner cylinder 20 at the maximum pressure of feed of the circuit.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Gripping On Spindles (AREA)
  • Fluid-Pressure Circuits (AREA)
EP02004445A 2001-02-28 2002-02-26 Linear actuator of cylindrical type Withdrawn EP1239166A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITUD010039 2001-02-28
IT2001UD000039A ITUD20010039A1 (it) 2001-02-28 2001-02-28 Attuatore lineare a pressione fluida a spinta differenziata costituito da cilindri coassiali

Publications (1)

Publication Number Publication Date
EP1239166A1 true EP1239166A1 (en) 2002-09-11

Family

ID=11460526

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02004445A Withdrawn EP1239166A1 (en) 2001-02-28 2002-02-26 Linear actuator of cylindrical type

Country Status (2)

Country Link
EP (1) EP1239166A1 (it)
IT (1) ITUD20010039A1 (it)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018065670A1 (en) 2016-10-06 2018-04-12 Tmk Energiakoura Oy Arrangement for controlling a hydraulic actuator in a working device and an energy-wood grapple

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1426506A1 (de) * 1962-05-26 1969-03-13 Hick Dr Walter Vorrichtung fuer hydraulische Kraftuebertragung
DE1964076A1 (de) * 1969-12-22 1971-06-24 Rexroth Gmbh G L Arbeitszylinder mit Eilgangkolben
EP0914896A2 (de) * 1997-10-25 1999-05-12 NIMAK Automatisierte Schweisstechnik GmbH Schweisszangenzylinder

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1426506A1 (de) * 1962-05-26 1969-03-13 Hick Dr Walter Vorrichtung fuer hydraulische Kraftuebertragung
DE1964076A1 (de) * 1969-12-22 1971-06-24 Rexroth Gmbh G L Arbeitszylinder mit Eilgangkolben
EP0914896A2 (de) * 1997-10-25 1999-05-12 NIMAK Automatisierte Schweisstechnik GmbH Schweisszangenzylinder

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018065670A1 (en) 2016-10-06 2018-04-12 Tmk Energiakoura Oy Arrangement for controlling a hydraulic actuator in a working device and an energy-wood grapple
EP3523541A4 (en) * 2016-10-06 2020-05-27 TMK Energiakoura OY ARRANGEMENT FOR CONTROLLING A HYDRAULIC ACTUATOR IN A WORKING DEVICE AND AN ENERGY WOOD GRIPPER

Also Published As

Publication number Publication date
ITUD20010039A1 (it) 2002-08-28

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